1. Field of the Invention
This invention relates to growth containers such as petri dishes used to grow laboratory organisms, and more particularly to an improved growth container and method of growing and collecting specimens of pathogenic and other laboratory organisms.
2. Description of the Prior Art
Glass bottles have typically been used in the past for laboratory growth of fungi and similar microbiotic organisms. A cap is provided for the bottle, with the cap normally cracked slightly open to exchange the necessary gases for fungal growth. Glass bottles and caps are not permeable to gases, whereas styrene is permeable. This type of growth environment has several problems. First, it does not provide for the regulation of gases or moisture within the bottle. Excess moisture resulting from condensation within the bottle can collect on the growth medium, thereby selecting for a surplus of bacteria and preventing fungal growth. The excess moisture condenses on the interior wall of the bottle and flows back into the growth medium, diluting antibiotics in the primary selected media. Furthermore, when a sample is removed from the bottle it is often difficult to trace the exact location from which it was taken, thus making a complete analysis difficult. Another problem is that, when the media inside the bottle is too wet, it is more difficult to handle the bottle because the surface of the media tends to flow when the bottle is turned. On the other hand, if the cap is left open too far the interior of the bottle can become excessively dry. Also, it is necessary to take the cap off to remove a sample, creating a danger that harmful pathogenic spores will escape from the bottle.
Specimens are normally removed from the bottle by means of a wire loop at the end of a tube. The specimens are then mixed on a slide for viewing under a microscope, and in the mixing process the specimens are sometimes destroyed. In addition, it is difficult to clearly identify and mark the exact location of the fungus as it is growing because of the refraction of the glass bottle wall; typical marking pens do not adhere to glass.
Various petri dish containers have also been devised for growing microorganisms. In U.S. Pat. No. 4,294,924 to Pepicelli et al. a container for growing anaerobic microorganisms has a cone-shaped dish and a matching cone-shaped cover with an agar medium contained between the two. No air vents are provided, nor is there any positive moisture control within the container. U.S. Pat. No. 4,299,921 to Youssef discloses a petri dish with a filter gasket attached to the cover to prevent contamination from outside the dish. U.S. Pat. No. 4,160,700 to Boomus et al. discloses a petri dish and lid with mating annular walls, in which annular flanges are provided on the dish and lid to facilitate opening the enclosure with one hand. In U.S. Pat. No. 3,769,936 to Swanson et al. the cover for a simple petri dish is provided with a small orifice for introducing materials into the dish without removing the cover, with a tab or resilient strip normally covering the orifice. In U.S. Pat. No. 2,348,448 to Brewer a petri dish is provided with a cover having a center recess in its lower surface to provide a space for organism growth. Placement of the cover over a growth medium in the dish provides an anaerobic environment.
While each of the above dish devices appear to provide useful growth environments, none of them provide for moisture regulation to prevent either an excessive build-up of moisture or an excessively dry environment, none of them provide a mechanism for mounting a specimen on a slide without the danger of destroying the specimen, and except for U.S. Pat. No. 3,769,936 none of them have the capability of accessing the interior of the container without removing the cover.